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Observed in Controlled Clinical Studies: Atracurium was well tolerated and produced few adverse reactions during extensive clinical trials. Most adverse reactions were suggestive of histamine release. In studies including 875 patients, atracurium was discontinued in only one patient (who required treatment for bronchial secretions) and six other patients required treatment for adverse reactions attributable to atracurium (wheezing in one, hypotension in five). Of the five patients who required treatment for hypotension, three had a history of significant cardiovascular disease. The overall incidence rate for clinically important adverse reactions, therefore, was 7/875 or 0.8%.

Table 1 includes all adverse reactions reported attributable to atracurium during clinical trials with 875 patients.

TABLE 1: PERCENT OF PATIENTS REPORTING ADVERSE REACTIONS Adverse Reaction Initial Atracurium Dose (mg/kg)

  0.00 - 0.30
(n = 485)
0.31 - 0.50*
(n = 366)
≥ 0.60
(n = 24)
(n = 875)
Skin Flush 1.0% 8.7% 29.2% 5.0%
Erythema 0.6% 0.5% 0% 0.6%
Itching 0.4% 0% 0% 0.2%
Wheezing/Bronchial Secretions 0.2% 0.3% 0% 0.2%
Hives 0.2% 0% 0% 0.1%
*Includes the recommended initial dosage range for most patients.

Most adverse reactions were of little clinical significance unless they were associated with significant hemodynamic changes. Table 2 summarizes the incidences of substantial vital sign changes noted during atracurium clinical trials with 530 patients, without cardiovascular disease, in whom these parameters were assessed.


Vital Sign Change Initial
0.00 - 0.30
(n = 365)
0.31 - 0.50*
(n = 144)
≥ 0.60
(n = 21)
(n = 530)
Mean Arterial Pressure
  Increase 1.9% 2.8% 0% 2.1%
  Decrease 1.1% 2.1% 14.3% 1.9%
Heart Rate
  Increase 1.6% 2.8% 4.8% 2.1%
  Decrease 0.8% 0% 0% 0.6%

*Includes the recommended initial dosage range for most patients.

Observed in Clinical Practice: Based on initial clinical practice experience in approximately 3 million patients who received atracurium in the U.S. and in the United Kingdom, spontaneously reported adverse reactions were uncommon (approximately 0.01% to 0.02%). The following adverse reactions are among the most frequently reported, but there are insufficient data to support an estimate of their incidence:

General: Allergic reactions (anaphylactic or anaphylactoid responses) which, in rare instances, were severe (e.g., cardiac arrest)

Musculoskeletal: Inadequate block, prolonged block

Cardiovascular: Hypotension, vasodilatation (flushing), tachycardia, bradycardia

Respiratory: Dyspnea, bronchospasm, laryngospasm

Integumentary: Rash, urticaria, reaction at injection site

There have been rare spontaneous reports of seizures in ICU patients following long-term infusion of atracurium to support mechanical ventilation. There are insufficient data to define the contribution, if any, of atracurium and/or its metabolite laudanosine. (See PRECAUTIONS: Long-Term Use in Intensive Care Unit [lCU]).